The present invention relates to an eyepiece image device installed in products such as head mount displays (HMDs). In a concrete sense, the image display device presented as the present invention is an optical device located in front of an eye of the observer, which guides image light projected from components such as a liquid crystal display (LCD) to an eye of the observer so that he or she visually recognizes an image. The present invention is mainly intended to achieve an eyepiece image device that does not block the field of vision of the observer while offering a natural wearability, and to decrease the size of the structure and achieve a stylish shape.
In recent years, demand is growing for wearable devices, defined as devices that can be attached to the body of users for use, such as HMDs used by attaching to the head. Furthermore, to name a few, various types of sensor devices and image display devices including LCDs have been downsized to a size installable in wearable devices; wearable devices coming with those devices are being developed at a rapid pace.
For example, conventional HMDs are disclosed in patent documents 1 through 3. The conventional HMDs disclosed in them have a common structure in which image light projected from the display element is propagated in the direction of the width of the eyes of the observer (horizontal direction) in the prism and guided to the optical pupils.